Another risk to consider is that normally one can just trade the Yen based upon the Nikkei (Nikkei up means weak Yen and vice versa) But lately one can see how the increase have affected the Yen and makes it a bit more jumpy. When checking various Yen pairs one can easily spot choppy daily, 240 and 60 min charts.
This one is however starting to look over valued on the and also have a divergence on the weekly chart. It is a choppy chart on the 60 min as well but the best indicator there is the 100 MA which may present the best entry level to go short. Just keep an eye on Nikkei and be flexible and you can make tons on pips on the Yen.